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Electronic supplementary information

Influence of 2,2-bithiophene and thieno[3,2-b] thiophene units on the photovoltaic

performance of benzodithiophene-based wide-bandgap polymers

Xuexue Pan,‡a,b Wentao Xiong,‡b Tao Liu,b Xiaobo Sun,*b Lijun Huo,*b Donghui Wei,c Mingming Yu,c

Minfang Han*a and Yanming Sun*b

a School of Chemical and Environmental Engineering, China University of Mining & Technology(Beijing), Beijing

100083, P. R. China. E-mail: hanminfang@sina.com

b Heeger Beijing Research and Development Center, School of Chemistry and Environment, Beihang University,

Beijing 100191, P. R. China. E-mail: sunxb@buaa.edu.cn; huolijun@buaa.edu.cn; sunym@buaa.edu.cn

c The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, Henan Province 450001, P.

R. China.

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C.This journal is © The Royal Society of Chemistry 2017

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-2.70

-4.95

S

S

S

S

OOS

S

S

S

S

S

S

S

P2

SS

S

S

OOS

SS

S

S

S

S

S

P1

-2.63

-4.85

LUMO

HOMO

Figure S1. Theory calculated HOMO and LUMO electron density distributions for P1 and P2 by the DFT calculation at B3LYP/6-31G level

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Figure S2. Map of the DFT electrostatic potential (ESP) surfaces of P1 (up) and P2 (down), dark color

indicates greater negative charge, while white and grey colors indicate positive charges.

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0.0 0.2 0.4 0.6 0.8 1.0-12

-10

-8

-6

-4

-2

0

P1:PC70BM1:1 (2% DIO) P1:PC70BM1:1.5(2% DIO) P1:PC70BM1:2 (2% DIO)

Voltage(v)

Curr

ent D

ensi

ty(m

A/cm

2 )

(a)

0.0 0.2 0.4 0.6 0.8 1.0-12

-10

-8

-6

-4

-2

0 P1:PC70BM(0% DIO) P1:PC70BM(1% DIO) P1:PC70BM(2% DIO) P1:PC70BM(3% DIO)

Voltage(v)

Curr

ent D

ensi

ty(m

A/cm

2 )

(b)

Figure S3. J-V curves of P1:PC70BM active layer a) different blend ratios (DIO 2%) and b) different concentration of DIO(P1:PC70BM=1:1.5).

300 400 500 600 7000

10

20

30

40

50

60

70

P1:PC70BM1:1 (2% DIO) P1:PC70BM1:1.5(2% DIO) P1:PC70BM1:2 (2% DIO)

EQE(

%)

Wavelength(nm)

(a)

300 400 500 600 7000

10

20

30

40

50

60

70

P1:PC70BM(0% DIO) P1:PC70BM(1% DIO) P1:PC70BM(2% DIO) P1:PC70BM(3% DIO)

EQE(

%)

Wavelength(nm)

(b)

Figure S4. EQE curves of P1:PC70BM active layer a) different blend ratios (DIO 2%) and b) different concentration of DIO (P1:PC70BM =1:1.5).

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Table S1. Photovoltaic parameters of PSCs with P1:PC70BM active layer in different blend ratios and different concentration of DIO

Ratio of D:A (w/w) DIO (%) VOC (V) JSC (mA/cm2) FF (%) PCEave (%) PCEmax (%)

1:1 0.87 8.97±0.01 70.8±0.00 5.49±0.02 5.51

1:1.5 0.86 11.00±0.06 72.9±0.00 6.86±0.07 6.93

1:22

0.86 9.27±0.01 66.1±0.01 5.26±0.04 5.30

0 0.92 7.09±0.03 47.2±0.01 3.06±0.05 3.11

1 0.87 9.43±0.01 70.4±0.00 5.79±0.05 5.84

2 0.86 11.00±0.06 72.9±0.00 6.86±0.07 6.931:1.5

3 0.85 9.57±0.05 70.4±0.00 5.75±0.05 5.80

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0.0 0.2 0.4 0.6 0.8 1.0-10

-8

-6

-4

-2

0 P2:PC70BM 1.5:1 (1% DIO) W33:PC70BM 1:1 (1% DIO) W33:PC70BM 1:1.5(1% DIO)

Voltage(v)

Curr

ent D

ensi

ty(m

A/cm

2 )

(a)

0.0 0.2 0.4 0.6 0.8 1.0-10

-8

-6

-4

-2

0 P2:PC70BM(0% DIO) P2:PC70BM(1% DIO) P2:PC70BM(2% DIO)

Voltage(v)

Curr

ent D

ensi

ty(m

A/cm

2 )

(b)

Figure S5. J-V curves of P2:PC70BM active layer a) different blend ratios (DIO 1%) and b) different

concentration of DIO (P2:PC70BM=1:1).

300 400 500 600 7000

10

20

30

40

50

60

70

P2:PC70BM1.5:1(1% DIO) P2:PC70BM1:1 (1% DIO) P2:PC70BM1:1.5(1% DIO)

EQE(

%)

Wavelength(nm)

(a)

300 400 500 600 7000

10

20

30

40

50

60

70

P2:PC70BM(0% DIO) P2:PC70BM(1% DIO) P2:PC70BM(2% DIO)

EQE(

%)

Wavelength(nm)

(b)

Figure S6. EQE curves of P2:PC70BM active layer a) different blend ratios (DIO 1%) and b) different concentration of DIO (P2:PC70BM =1:1).

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Table S2. Photovoltaic parameters of PSCs with P2:PC70BM active layer in different blend ratios and different concentration of DIO

Ratio of D:A (w/w) DIO (%) VOC (V) JSC (mA/cm2) FF (%) PCEave (%) PCEmax (%)

1.5:1 0.88 7.37±0.03 48.2±0.01 3.14±0.04 3.18

1:1 0.85 8.55±0.04 53.1±0.01 3.87±0.05 3.92

1:1.5

1

0.85 7.91±0.01 50.3±0.00 3.37±0.03 3.40

0 0.88 5.60±0.01 40.5±0.00 2.00±0.02 2.02

1:1 1 0.85 8.55±0.04 53.1±0.01 3.87±0.05 3.92

2 0.86 8.51±0.01 51.1±0.00 3.74±0.03 3.77

Table S3. The hole mobilities of P1 and P2 for pristine and blend films

sample Hole moobilities(cm2 V−1 s−1)

P1 1.62×10-3

P2 1.17×10-3

P1:PC70BM (1:1.5) 9.86×10-4

P2:PC70BM (1:1) 6.82×10-4

P1:PC70BM (1:1.5, 2%DIO) 1.22×10-3

P2:PC70BM (1:1, 1%DIO) 8.60×10-4

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(a) (b)

Figure S7. AFM height images of P1 neat film, and b) P2 neat film.

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1 2 qxy (A

-1)

P1 P2

inte

nsity

1 2qxy (A

-1)

P1:PC70BM P2:PC70BM

Inte

nsity

0.5 1.0 1.5 2.0qz(A

-1)

P1 P2

Inte

nsity

0.5 1.0 1.5 2.0qz (A

-1)

P1:PC70BM P2:PC70BM

Inte

nsity

(a)

(b) (d)

(c)

Figure S8. GIWAXS patterns of neat polymer and blend films. Out-of-plane linecut profiles of pristine

films (a) and blend films (c) and In-plane linecut profiles of pristine films (b) and blend films (d).